1. Field of the Art
The present invention relates in general to an automatic blood pressure monitoring system, and in particular to such a system which automatically obtains a measure of an blood pressure upon detection of abnormality in the degree of saturation of oxygen in the blood of a subject being monitored.
2. Related Art Statement
There is known in the art an automatic blood pressure monitoring system having an inflatable cuff which is wound around a part of a subject or living body to be monitored, so as to oppress the part, and also having determining means which determines a measure of blood pressure based on fluctuations of pulse waves that are caused in association with variation in the pressure in the inflatable cuff. In order to capture such fluctuations of the pulse waves, a variety of indications or signs are utilized such as: appearance and disappearance of Korotkov's sounds which are heard at the part of the subject, while the cuff is deflated; change in the magnitude of oscillations of the pressure in the cuff which are caused in synchronous relationship with heartbeats of the subject; or change in the magnitude of pulsations on the surface of the wall of an artery that are detected by means of ultrasonic wave. A conventional automatic monitoring system of such a type is adapted to obtain blood pressure measurements, according to starting signals supplied periodically, for the purpose of, for example, monitoring a patient (subject) during or after a surgical operation procedure.
3. Problem Solved by the Invention
In the above-identified type of automatic monitoring system, a measure of blood pressure is not necessarily obtained at the time the subject being monitored is brought into an abnormal state with respect to the degree of saturation of oxygen in the blood, due to shock or cyanosis, since such measurement is conducted at regular intervals of time. That is, the conventional system is not able to obtain a measure of blood pressure at the time the measure is clinically needed for monitoring the condition of the subject. An automatic monitoring system for monitoring a subject's blood pressure during or after a surgical operation, is required from the clinical viewpoint to be able to obtain a measure of blood pressure at the very time the subject is brought into an abnormal state.
Meanwhile, it is possible to obtain a measure of blood pressure at the time approximate to the time of occurrence of an abnormality of the subject, by means of using starting signals generated at shortened intervals and performing the operation of obtaining blood pressure measurements at shortened cycles. This method is, however, disadvantageous since the subject suffers unnecessary oppression by the inflatable cuff that is repeatedly inflated and deflated, and may have congestion at the part around which the cuff is wound.